Method and system for location estimation

ABSTRACT

Several methods and systems for location estimation are disclosed. In an embodiment, the method includes performing a primary wireless scan to identify a first set of access points at a user location associated with a first user location estimate. A secondary wireless scan is performed at pre-defined time intervals subsequent to the primary wireless scan. A set of access points is identified corresponding to each secondary wireless scan. The method further comprises detecting a presence or an absence of user motion based on a number of shared access points between the first set of access points and a set of access points corresponding to each secondary wireless scan. A current user location is estimated to be the first user location estimate if the user motion is detected to be absent, or a second user location estimate computed based on geolocation signals if the user motion is detected to be present.

TECHNICAL FIELD

The present disclosure generally relates to the field of locationestimation.

BACKGROUND

In recent times, handheld device applications, such as, for example,applications related to location based advertising, social networking,reminder services and the like, are driving the need for low powerestimation of user's location. The handheld device applications areconfigured to be executed continuously at an application layer backendso as to monitor the user's locations and trigger specific actions at anapplication level upon the user's arrival at, and departure from, areasof interest. For example, such applications may recommend nearbyshopping, eating and/or entertainment options or even providenotifications of friends who are currently in the area, upon estimatingthe user's location.

Pursuant to an exemplary scenario, satellite based navigation systems(e.g., Global Navigation Satellite Systems (GNSS)) with appropriateperiodicity (e.g., an appropriate duty cycle) may be implemented toachieve periodic estimation of user location. The handheld deviceapplications may utilize the GNSS location estimation to triggerspecific actions at the application level. However, the GNSS sensingperiodicity is both fixed and independent of user context. For example,even if the user is stationary or positioned in an environment havinglow mobility conditions for an extended period of time (for example, theuser may be at home or in an office where there is limited mobility),the sensing periodicity is maintained. Given that GNSS location sensingconsumes up to 20 milliamperes (mA) when 1-minute of periodicity isused, sizable amount of power could be consumed during such an exercise,which may be undesirable.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key or essentialfeatures of the claimed subject matter, nor is it intended to be used asan aid in determining the scope of the claimed subject matter.

Various methods and systems for location estimation are disclosed. In anembodiment, a location estimation method includes performing a primarywireless scan to identify a first set of access points at a userlocation. The user location is associated with a first user locationestimate. The location estimation method further includes performing asecondary wireless scan at pre-defined time intervals subsequent to theprimary wireless scan, wherein a set of access points is identifiedcorresponding to each secondary wireless scan, and wherein for eachsecondary wireless scan, a number of shared access points is identifiedand compared with a pre-defined threshold value. A shared access pointis an access point identified to be present in the first set of accesspoints and the set of access points corresponding to the secondarywireless scan. The location estimation method further includes detectingwith a location estimation device, (1) a presence of user motion if thenumber of shared access points is less than or equal to the pre-definedthreshold value for a pre-defined number of consecutive secondarywireless scans, or (2) an absence of the user motion from the userlocation if the number of shared access points is greater than thepre-defined threshold value for the pre-defined number of consecutivesecondary wireless scans. The location estimation method furtherincludes estimating current user location with the location estimationdevice, based on the first user location estimate if the absence of theuser motion is detected, or a second user location estimate computedbased on geolocation signals if the presence of the user motion isdetected.

In an embodiment, a location estimation system is provided. The locationestimation system includes a Wi-Fi module and a geolocation module. TheWi-Fi module includes a Wi-Fi scan module and a Wi-Fi motion detectorcommunicatively associated with the Wi-Fi scan module. The Wi-Fi scanmodule is configured to perform a primary wireless scan to identify afirst set of access points at a user location. The user location isassociated with a first user location estimate. The Wi-Fi scan module isfurther configured to perform a secondary wireless scan at pre-definedtime intervals subsequent to the primary wireless scan. A set of accesspoints is identified corresponding to the each secondary wireless scan.The Wi-Fi motion detector is configured to identify a number of sharedaccess points for each secondary wireless scan, where a shared accesspoint is an access point identified to be present in the first set ofaccess points and the set of access points corresponding to thesecondary wireless scan. The Wi-Fi motion detector is further configuredto compare the number of shared access points with a pre-definedthreshold value to thereby identify (1) a presence of user motion if thenumber of shared access points is less than or equal to the pre-definedthreshold value for a pre-defined number of consecutive secondarywireless scans, or (2) an absence of the user motion from the userlocation if the number of shared access points is greater than thepre-defined threshold value for the pre-defined number of consecutivesecondary wireless scans. The geolocation module is communicativelyassociated with the Wi-Fi module and includes a geolocationdetermination module. The geolocation determination module is configuredto estimate a current user location based on the first user locationestimate if the absence of the user motion is detected, or, a seconduser location estimate computed based on geolocation signals if thepresence of the user motion is detected.

Additionally, in an embodiment, a method for estimating a location of anobject based on object motion detection is disclosed. In an embodiment,the method includes performing a primary wireless scan to identify afirst set of access points at an object location. The object location isassociated with a first object location estimate. The method furtherincludes performing a secondary wireless scan at pre-defined timeintervals from the primary wireless scan, wherein a set of access pointsis identified corresponding to each secondary wireless scan, and whereinfor each secondary wireless scan, a number of shared access points isidentified and compared with a pre-defined threshold value. A sharedaccess point is an access point identified to be present in the firstset of access points and the set of access points corresponding to thesecondary wireless scan. The method further includes detecting with anelectronic device, (1) a presence of object motion if the number ofshared access points is less than or equal to the pre-defined thresholdvalue for a pre-defined number of consecutive secondary wireless scans,or (2) an absence of the object motion from the object location if thenumber of shared access points is greater than the pre-defined thresholdvalue for the pre-defined number of consecutive secondary wirelessscans.

Other aspects and example embodiments are provided in the drawings andthe detailed description that follows.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts an example environment for illustrating periodic locationestimation in accordance with an example scenario;

FIG. 2 is a simplified block diagram of an example location estimationsystem in accordance with an embodiment;

FIG. 3 depicts a schematic representation for illustrating examplemotion detection in accordance with an embodiment;

FIG. 4 depicts a plurality of charts associated with example motiondetection in accordance with an embodiment;

FIG. 5 illustrates a flow diagram of a first example location estimationmethod in accordance with an example embodiment;

FIGS. 6A and 6B illustrate a flow diagram of a second example locationestimation method in accordance with an example embodiment; and

FIG. 7 illustrates a flow diagram of a method for estimating a locationof an object based on object motion detection in accordance with anexample embodiment.

The drawings referred to in this description are not to be understood asbeing drawn to scale except if specifically noted, and such drawings areonly exemplary in nature.

DETAILED DESCRIPTION

Many handheld device applications, such as, for example, applicationsrelated to like location based advertising, social networking, reminderservices and the like, are driving the need for low power estimation ofuser's location. The handheld device applications are configured to beexecuted continuously at the application layer backend so as to monitorthe user's locations and trigger specific actions at an applicationlevel upon the user's arrival at, and departure from, areas of interest.Pursuant to an example scenario, satellite based navigation systems(e.g., Global Navigation Satellite Systems (GNSS)) with appropriateperiodicity (e.g., an appropriate duty cycle) may be implemented toachieve periodic estimation of user location. For example, the handhelddevice applications may utilize such GNSS location estimation to triggerspecific actions at the application level. The periodic locationestimation is further explained with reference to an example environmentin FIG. 1.

FIG. 1 depicts an example environment 100 for illustrating periodiclocation estimation in accordance with an example scenario. Theenvironment 100 depicts a user 102 on a floor 106 of a multi-storiedbuilding 108. The multi-storied building 108 is depicted to be disposedamong a plurality of buildings structures, such as building structures110, 112, 114 and the like. The environment 100 further depicts anotheruser 104 on a street 116 adjoining the plurality of building structures.Each user from among the users 102 and 104 is depicted to be associatedwith an electronic device. For example, the user 102 is depicted to beassociated with an electronic device 118 and the user 104 is depicted tobe associated with an electronic device 120. It is understood that theusers 102 and 104 may be associated with one or more of such electronicdevices. Examples of the electronic devices 118 and 120 may not onlyinclude handheld devices like mobile phones, Smartphones, laptops andtablet computers but may also include wearables or accessories likewatches, pair of glasses and the like. The electronic devices 118 and120 may include a number of applications, such as those related tolocation based advertising, social networking, reminder services and thelike, which are configured to be executed continuously in theapplication backend so as to monitor a user's locations and triggerspecific actions at an application level upon a user's arrival at, or,departure from, areas of interest.

In an exemplary scenario, the electronic devices 118 and 120 may beconfigured to communicate with satellite based navigation systems (e.g.,Global Navigation Satellite Systems (GNSS)) with appropriate periodicity(e.g., duty cycle) for periodic estimation of user location. Forexample, the electronic devices 118 and 120 may sense and communicatewith a plurality of satellites like satellites 122 and 124 for locationestimation purposes. However, the sensing periodicity is both fixed andindependent of user context. For example, even though the user 102 is onthe floor 106 and accordingly is relatively stationary or is in a lowmobility condition for an extended period of time, the sensingperiodicity is maintained. Similarly, the sensing periodicity ismaintained to be the same for the user 104, who is walking on the street116. Given that GNSS location sensing consumes up to 20 milliamperes(mA) when 1-minute of periodicity is used, sizable amount of power couldbe consumed during such an exercise, which may be undesirable.

In certain exemplary scenarios, sensor based motion detection may beemployed in the electronic devices, such as the electronic devices 118and 120 for detecting user movement. For example, the electronic devicesmay include an accelerometer to detect user movement. A satellite basedlocation estimation (also referred to hereinafter as satellite basedpositioning) may be triggered upon detection of user movement. Forexample, only when ‘Acceleration>threshold’, satellite based positioningis used for location estimation. An accelerometer typically consumesabout 0.1 mA, thereby saving satellite sensing/computation power whenuser is completely stationary. However, sensors such as theaccelerometer are associated with high sensitivity to minimal usermovement and electronic device orientation changes. For example, a usermoving within a cubicle in his/her office may trigger motion detection.Moreover, orientation changes can trigger motion detection due togravity leakage. As a result, power saving in realistic scenarios isvery limited due to the high sensitivity of such sensor based motiondetectors. Furthermore, it is observed that motion detection is nottriggered in some vehicular use cases, such as for example, in scenariosinvolving vehicles driving at constant velocity (for example, vehiclesdriving in cruise control mode).

In another exemplary scenario, location estimation may be implementedusing wireless access points, which offers a low power alternative tosatellite based positioning in many areas. More specifically, thewireless access point based location estimation (also referred tohereinafter as Wi-Fi based positioning) involves computing a userlocation based on wireless access points and their correspondingreceived signal strength indication (RSSI) or their time of flight (TOF)measurements. However, location estimation based on Wi-Fi basedpositioning is associated with several limitations. For example,location estimation using the Wi-Fi based positioning necessitates theprior knowledge of access point locations. However, obtaining thelocation co-ordinates of the access points (especially for indoorlocations) for the Wi-Fi based positioning is difficult and cumbersome.In typical indoor locations, there is no single vendor with access pointdatabase covering a large fraction of indoor areas. Moreover, in typicalscenarios, in absence of Wi-Fi access point database residing in theuser device, the Wi-Fi based positioning is implemented in variousservers of private companies, which may require frequent host and webaccess, which significantly increases power consumption (for example, upto 100 s of mA).

Various embodiments of the present technology, however, provide methodsand systems for low-power location estimation that are capable ofovercoming these and other obstacles and providing additional benefits.Accordingly, Wi-Fi and satellite based positioning are collectivelyutilized in location estimation. More specifically, Wi-Fi scans are usedto determine if the user has moved or not. This is then used to modulatea call to satellite location estimation. This decreases powerconsumption significantly in indoor pedestrian and stationaryconditions. An example location estimation system is explained withreference to FIG. 2.

FIG. 2 is a simplified block diagram of an example location estimationsystem 200 (hereinafter referred to as system 200) in accordance with anembodiment. In FIG. 2, the system 200 is depicted to include a Wi-Fimodule 202, a geolocation module 204, a controller module 206 and asensor module 208. The Wi-Fi module 202 is depicted to include a Wi-Fiscan module 210 and a Wi-Fi motion detector 212. The geolocation module204 is depicted to include a geolocation motion detector 214 and ageolocation determination module 216. The Wi-Fi module 202, thegeolocation module 204, the controller module 206 and the sensor module208 are communicatively associated with each other via bus 218. Examplesof the bus 218 may include, but is not limited to, a data bus, a controlbus and the like. The bus 218 may be, for example, a serial bus, aunidirectional bus or a bi-directional bus.

In accordance with an example implementation, the system 200 may beeither a physical module (e.g., an integrated circuit chip or package)or a software module. In accordance with a second exampleimplementation, however, the system 200 is a location estimation device(or location estimation machine) specifically configured to implementvarious embodiments of the present technology. In an embodiment, thesystem 200 may be included within an electronic device, such as theelectronic devices 118 and 120 of FIG. 1. Accordingly, the system 200may be included, wholly or in a distributed manner, within one ofhandheld devices like mobile phones, Smartphones, laptops and tabletcomputers and/or wearables or accessories like watches, pair of glassesand the like. In an example distributed implementation of the system200, one or more components, such as the geolocation module 204(including the geolocation motion detector 214 and the geolocationdetermination module 216) may be embedded within a host processor of ahandheld device, whereas the Wi-Fi module 202 including the Wi-Fi scanmodule 210 and the Wi-Fi motion detector 212 may be implemented externalto the host processor. The Wi-Fi module 202 and the geolocation module204 may be in communication with each other and in conjunction withother components, such as the controller module 206 and the sensormodule 208 together configure the system 200. In such a configuration,the Wi-Fi module 202 wakes up the host processor upon detection of usermotion (the detection of user motion is explained later) therebyenabling the host processor to sleep for longer durations and savepower. Upon waking of the host processor, the geolocation module 204 inthe host processor is configured to compute the user location usinggeolocation signals to facilitate user location estimation. As notedabove, all components of the system 200 may also be implemented whollyin a handheld device. The system 200 is configured to continuously runin the background and perform location estimation and provision locationinformation to one or more applications, which may need such informationfor performing related tasks. Alternatively, the handheld device may beconfigured to facilitate a display of estimated location, for example ona digitized map of a geographical area on the display of the handhelddevice. It is noted that the system 200, in some example scenarios, mayperform such location estimation irrespective of whether a user isactively seeking location information.

In an embodiment, various components of the system 200, such as theWi-Fi module 202 and its components such as the Wi-Fi scan module 210and the Wi-Fi motion detector 212, the geolocation module 204 and itscomponents, such as the geolocation motion detector 214 and thegeolocation determination module 216, the controller module 206, thesensor module 208 and the bus 218 may be implemented as hardware,software, firmware or any combination thereof. For example, one or morecomponents of the system 200 may be embodied as a multi-core processor,a single-core processor, or a combination of one or more multi-coreprocessors and one or more single-core processors. For example, one ormore modules of the system 200 may be embodied as one or more of variousprocessing devices, such as a coprocessor, a microprocessor, acontroller, a digital signal processor (DSP), processing circuitry withor without an accompanying DSP, or various other processing devicesincluding integrated circuits such as, for example, an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), a microcontroller unit (MCU), a hardware accelerator, aspecial-purpose computer chip, or the like. In an embodiment, one ormore components of the system 200 may be configured to executehard-coded functionality. In an embodiment, the one or more componentsof the system 200 may be embodied as an executor of softwareinstructions, wherein the instructions may specifically configure thesystem 200 to perform the algorithms and/or operations described hereinwhen the instructions are executed. One or more modules of the system200 may include, among other things, a clock, an arithmetic logic unit(ALU) and logic gates configured to support an operation of the system200. In an embodiment, the system 200 is embodied at least partially inthe form of the integrated circuit.

In an embodiment, the sensor module 208 may include one or more initialmeasurement unit (IMU) sensors such as a gyroscope (for sensing angularvelocity), an accelerometer (for sensing acceleration) and the like. Insome embodiments, the system 200 may include fewer or more number ofcomponents than those depicted in FIG. 2. For example, in someembodiments, the system 200 may preclude the sensor module 208. In sucha case, the sensor module 208 may be included within the electronicdevice or may be external to the electronic device and may becommunicatively associated with the system 200.

In an embodiment, the Wi-Fi scan module 210 may be embodied as atransceiver, which is configured to facilitate wireless accessconforming to WLAN standards/specifications, such as the IEEE 802.11a/b/c/g specifications. In some embodiments, the transceiver may beconfigured to conform to specifications for NFC communication, Bluetoothinformation exchange and/or Zigbee network access. In an embodiment, theWi-Fi scan module 210 is configured to perform a primary wireless scanto identify a first set of access points at a user location. Forexample, if the user is located on floor 106 of the multi-storiedbuilding 108 of FIG. 1, then the Wi-Fi scan module 210 may perform theprimary wireless scan to identify (1) one or more access pointspositioned in the floor 106 and (2) one or more access points positionedin the vicinity of the floor 106 (such as for example, one or morefloors immediately above or below the floor 106 in the multi-storiedbuilding 108), which may together configure the first set of accesspoints. The user location is associated with a first user locationestimate. In an example scenario, the first user location estimate, suchas a three-dimensional location estimate of the user on the floor 106may have been previously computed, for example by using triangulation ofgeolocation signals received from three or more satellites (for example,signals received from GNSS satellites), and as such, the user locationestimate of the user may already be known prior to performing theprimary wireless scan. In an embodiment, the first user locationestimate may be computed using the geolocation determination module 216prior to performing of the primary wireless scan by the Wi-Fi scanmodule 210. In another embodiment, the first user location estimate mayhave been computed using Wi-Fi based positioning (for example, usingRSSI or TOF measurements from nearby access points), prior to performingthe primary wireless scan by the Wi-Fi scan module 210.

In an embodiment, the Wi-Fi scan module 210 is further configured toperform a secondary wireless scan at pre-defined time intervals from theprimary wireless scan. A set of access points is identifiedcorresponding to each secondary wireless scan. In an illustrativeexample, a pre-defined time interval may be chosen to be ten seconds.Accordingly, the Wi-Fi scan module 210 may be configured to perform asecondary wireless scan at every ten second interval (for example, at10, 20, 30 seconds and so on and so forth) from the completion of theprimary wireless scan. At each secondary wireless scan, the Wi-Fi scanmodule 210 identifies a set of access points. It is understood that thepre-defined time interval of ten seconds is included herein forillustration purposes and that the pre-defined time interval may bechosen to be any such time interval based on empirical data.

In an embodiment, the Wi-Fi motion detector module 212 is configured todetect a presence of one or more mobile access points. The term ‘mobileaccess point’ as used herein refers to a non-stationary access pointidentified to be present across one or more distant locations. Forexample, consider an access point deployed in a vehicle of the user. Ina case when the user is traveling in the vehicle, the access point willbe identified during each wireless scan performed from the vehicle,irrespective of a large change in user location. Such an access point isreferred to herein as a mobile access point. In other example scenario,a user may be associated with one or more other electronic devices,which may function as an access point during various use cases. Suchaccess points may be identified at various user locations and as suchall such access points are referred to as mobile access points. In somecases, the access points that are observed to be persistent in each scanin spite of change in all previously identified access points may alsoprovide an indication of the access points being mobile access points.In some example scenarios, the mobile access points may also beidentified using satellite based positioning. For example, access pointsdetected to be present at two different location estimates obtainedusing satellite based positioning may enable the identification ofmobile access points. The Wi-Fi motion detector 212 is furtherconfigured to eliminate the one or more mobile access points from thefirst set of access points and the set of access points corresponding toeach secondary wireless scan if the one or more mobile access points aredetected to be present.

In an embodiment, the Wi-Fi motion detector 212 is configured toidentify a presence of one or more duplicate entries in the first set ofaccess points and the set of access points corresponding to eachsecondary wireless scan, respectively, by disregarding last nibble ofmedia access control (MAC) identification (IDs) during access pointidentification. It is noted that a same physical access point mayadvertise multiple MAC IDs, which differ only in their last nibble (e.g.last group of alphanumeric characters from among a plurality ofalphanumeric characters configuring MAC IDs). As a result, the Wi-Fimotion detector 212 may wrongly interpret a same physical access pointas different access points and include the same physical access pointmultiple times during wireless scanning. Accordingly, the Wi-Fi motiondetector 212 is configured to disregard the last nibble of the MAC IDsduring wireless scanning, which may result in one or more duplicateentries in the first set of access points as well as in each set ofaccess points identified during one or more secondary wireless scans.The Wi-Fi motion detector 212 may further be configured to coalesce theone or more duplicate entries in the first set of access points and theset of access points corresponding to each secondary wireless scan,respectively, if the one or more duplicate access points are identifiedto be present.

After each wireless scan (including the primary wireless scan and thesecondary wireless scans), the Wi-Fi motion detector 212 is configuredto eliminate any mobile access point found to be present as well ascoalesce any duplicate entries therein. The Wi-Fi motion detector 212 isthen configured to identify, for each secondary wireless scan, a numberof shared access points between the first set of access points and a setof access points corresponding to each secondary wireless scan. TheWi-Fi motion detector 212 is further configured to compare the number ofshared access points with a pre-defined threshold value. For example, ifthe first set of access points identified during the primary wirelessscan includes access points A, B and C and if the set of access pointsin a secondary wireless scan includes access points B, C and D, then anumber of access points identified to be shared (or common) is two (forexample, access points B and C are identified to be common) and thisnumber of shared access points is compared with a pre-defined thresholdvalue. In an illustrative example, the pre-defined threshold value ischosen to be zero. Accordingly, the Wi-Fi motion detector 212 comparesthe number of shared access points, i.e. two in this case with thepre-defined threshold value (chosen to be zero) and stores the result ofthe comparison.

In an example scenario, the pre-defined threshold value may be chosen(for example, by the Wi-Fi motion detector 212) based on empirical dataassociated with various types of environment (for example, indoorenvironment, outdoor environment, rural environment, urban or semi-urbanenvironment and the like). For example, in areas with high access pointdensity, the pre-defined threshold value may be chosen to be a highernumber (for example, two or greater than two), whereas an area withlower access point density, the pre-defined threshold value may bechosen to be a smaller number (for example, zero or one). In anembodiment, the pre-defined threshold value may be determined based onan expected number of mobile access points in the surrounding area.

In an embodiment, the Wi-Fi motion detector 212 is configured to detect:(1) a presence of user motion if the number of shared access points isless than or equal to the pre-defined threshold value for a pre-definednumber of consecutive secondary wireless scans, or (2) an absence of theuser motion from the user location if the number of shared access pointsis greater than the pre-defined threshold value for the pre-definednumber of consecutive secondary wireless scans. As explained above,after each secondary wireless scan, a number of shared access points iscompared with the pre-defined threshold value and the result of thecomparison is stored by the Wi-Fi motion detector 212. If the result ofthe comparison corresponds to the number of shared access points beingless than or equal to the pre-defined threshold value for ‘m’ number ofconsecutive secondary wireless scans, then the Wi-Fi motion detector 212is configured to determine that the user has moved from the previouslydetermined user location associated with the first user locationestimate. The value of ‘m’ or the pre-defined number of consecutivesecondary wireless scans may be chosen based on empirical data. In anillustrative example, the value of ‘m’ may be chosen to be five. It isnoted that the value of ‘m’ may not be limited to five and any suchnumber may be chosen for motion detection purposes. If the result of thecomparison corresponds to the number of shared access points beinggreater than the pre-defined threshold value for ‘m’ consecutivesecondary wireless scans, then the Wi-Fi motion detector 212 isconfigured to determine that the user has not moved from the previouslydetermined user location associated with the first user locationestimate. In an embodiment, the Wi-Fi module 202 may be configured torepeat the steps of performing the primary wireless scan and thesecondary wireless scans, periodically, till the change in user locationfrom the previously determined user location is observed. The detectionof the change in the user location is further explained with referenceto FIG. 3.

FIG. 3 depicts a schematic representation 300 for illustrating examplemotion detection in accordance with an embodiment. The motion detection,(e.g., detection of the user motion) may be performed by the Wi-Fimotion detector 212 of the system 200 as explained with reference toFIG. 2. The schematic representation 300 displays an example user 302associated with an electronic device 304 including the system 200 (notshown in FIG. 3). The electronic device 304 may be embodied as one of ahandheld device, such as a mobile phone, a Smartphone, a laptop and atablet computer or even a wearable or an accessory, such as a watch or apair of glasses.

As explained above with reference to FIG. 2, the Wi-Fi scan module 210of the Wi-Fi module 202 performs a primary wireless scan at a userlocation to identify the first set of access points. Thereafter, theWi-Fi scan module 210 performs a secondary wireless scan at pre-definedtime intervals and the Wi-Fi motion detector 212 compares a number ofshared access points with a pre-defined threshold value at eachsecondary wireless scan to detect the presence of user motion.Accordingly, in the schematic representation 300, the user 302 isdepicted to be at first user location 306. A first user locationestimate associated with the first user location 306 may be determinedusing the geolocation determination module 216 in the system 200. TheWi-Fi scan module 210 may perform a primary wireless scan at the firstuser location 306 to receive signals from access points 308, 310, 312and 314. The access points 308, 310, 312 and 314 may accordingly beidentified to configure the first set of access points. The Wi-Fi scanmodule 210 may perform a secondary wireless scan after a pre-definedtime interval (for example, ten seconds) from the completion of theprimary wireless scan. The user 302 may have moved to a second userlocation 316 in the time elapsed between the primary wireless scan andthe secondary wireless scan. The Wi-Fi scan module 210 may identify aset of access points 312, 314, 318 and 320 at the second user location316. The Wi-Fi motion detector 212 may compare the first set of accesspoints and the set of access points corresponding to the second userlocation 316 to identify a number of shared access points. The Wi-Fimotion detector 212 may identify the number of shared access points tobe two (for example, access points 312 and 314). The Wi-Fi motiondetector 212 is further configured to compare the number of sharedaccess points to a pre-defined threshold value. In the illustrationdepicted by the schematic representation 300, the pre-defined thresholdvalue is chosen to be zero. It is understood that the value of thepre-defined threshold may be chosen based on a number of factors asexplained with reference to FIG. 2. The number of shared access points,i.e. two in this case, is compared with the pre-defined threshold value,i.e. zero and the result of the comparison (i.e. the number of sharedaccess points is greater than the pre-defined threshold value) is storedby the Wi-Fi motion detector 212 of the system 200.

The Wi-Fi scan module 210 is further configured to perform anothersecondary wireless scan at a pre-defined interval (for example, tenseconds) from the completion of the earlier secondary wireless scan. Theuser 302 may have moved to a third user location 322 in the time elapsedbetween the earlier secondary wireless scan and the subsequent secondarywireless scan. The Wi-Fi scan module 210 may identify a set of accesspoints 318, 320, 324 and 326 at the third user location 322. The Wi-Fimotion detector 212 may compare the first set of access points and theset of access points corresponding to the third user location 322 toidentify a number of shared access points. The Wi-Fi motion detector 212may identify the number of shared access points to be zero. The Wi-Fimotion detector 212 is further configured to compare the number ofshared access points to the pre-defined threshold value (for example,the zero value). The number of shared access points, i.e. zero in thiscase, is compared with the pre-defined threshold value, i.e. zero andthe result of the comparison (i.e. the number of shared access points isequal to the pre-defined threshold value) is stored by the Wi-Fi motiondetector 212.

As explained with reference to FIG. 2, the Wi-Fi motion detector 212 isconfigured to detect: (1) a presence of user motion if the number ofshared access points is less than or equal to the pre-defined thresholdvalue for a pre-defined number of consecutive secondary wireless scans,or (2) an absence of the user motion from the user location if thenumber of shared access points is greater than the pre-defined thresholdvalue for the pre-defined number of consecutive secondary wirelessscans. In this illustrative example, the pre-defined number ofconsecutive secondary wireless scans is chosen to be one, or, morespecifically the presence or absence of user motion is detected at everyinstant of wireless scanning. Accordingly, since the number of sharedaccess points is greater than the pre-defined threshold value at thesecond user location 316, the Wi-Fi motion detector 212 detects anabsence of user motion (or more specifically, absence of significantuser motion). However, at the third user location 322, since the numberof common access points is equal to the pre-defined threshold value, theWi-Fi motion detector 212 detects the presence of user motion. In someexample embodiments, such a technique of user motion detection based onaccess point visibility during successive wireless scans may be extendedto other applications, such as for example, tracking of assets in awarehouse and the like. More specifically, the presence of goods (orobjects) in a warehouse may be ascertained based on corresponding motiondetection (or lack of motion therefrom) based on access point visibilityduring successive wireless scans as will be explained later withreference to FIG. 7.

Referring now to FIG. 2, in an embodiment, the Wi-Fi motion detector 212is further configured to compute for each secondary wireless scan, adifference in received signal strength indication (RSSI) measurementsbetween the first set of access points and a set of access pointscorresponding to the each secondary wireless scan to assist in detectionof the user motion with finer resolution. For example, in addition tothe number of shared access points, a difference in RSSI (or time offlight or TOF) measurements may be computed to assist in detection ofuser motion. For example, if an RSSI measurement received from an accesspoint is observed to be decreasing over consecutive secondary wirelessscans, then the Wi-Fi motion detector 212 may be configured to determinethat the user is moving away from the access point and accordingly, usermotion may be detected with greater granularity/resolution based ondifference in RSSI measurements.

In an embodiment, the geolocation determination module 216 is configuredto estimate a current user location based on: (1) the first userlocation estimate if the absence of user motion is detected, or (2) asecond user location estimate computed based on geolocation signals ifthe presence of user motion is detected. More specifically, thegeolocation determination module 216 is configured to propagate theinitially computed first user location estimate if the absence of usermotion is detected. Accordingly, a location of the user may be estimatedto be user location associated with the first user location estimate.One or more applications in the electronic device associated with thesystem 200 may utilize the estimated location of the user for triggeringone or more specific actions at an application level upon a user'sarrival at, or, departure from, areas of interest. However, if the Wi-Fimotion detector 212 detects a presence of the user motion, then thegeolocation determination module 216 may compute the second userlocation estimate based on geolocation signals received at the new userlocation. For example, if it is determined that the user has moved fromthe floor 106 to the street 116 depicted in the environment 100 in FIG.1, then the geolocation determination module 216 is configured tocompute the second user location estimate based on the geolocationsignals received by the geolocation determination module 216 at the userlocation on the street 116.

In an embodiment, the controller module 206 is configured to detect if adifference between the second user location estimate and the first userlocation estimate (also referred to herein as the new user locationestimate and the old user location estimate, respectively) is greaterthan a pre-defined distance threshold. In an embodiment, the controllermodule 206 is configured to detect subsequent user motion based on thedifference between the second user location estimate and the first userlocation estimate. In an embodiment, the controller module 206 isconfigured to select one of the Wi-Fi motion detector 212 and thegeolocation motion detector 214 for facilitating the subsequent usermotion detection based on the detected difference. For example, if thedifference between the second user location estimate and the first userlocation estimate is greater than the pre-defined distance threshold,implying that the user is moving with a higher velocity, then thecontroller module 206 is configured to select the geolocation motiondetector 214 with associated periodicity to detect subsequent usermotion. In an example embodiment, the periodicity associated with thegeolocation motion detector 214 may be one-minute interval, implying asatellite scan every minute to receive geolocation signals from thesatellites. The geolocation determination module 216 may then computeuser locations at every minute and check for presence of user movementfrom the previously computed user location to detect subsequent usermotion.

In an embodiment, if the difference between the second user locationestimate and the first user location estimate is less than or equal tothe pre-defined distance threshold, implying, that the user is eitherstationary or moving with a relatively lower velocity, then thecontroller module 206 is configured to select the Wi-Fi motion detector212 with associated periodicity to detect subsequent user motion. In anexample embodiment, the periodicity associated with the Wi-Fi motiondetector 212 may be 15 seconds interval, implying a wireless scan every15 seconds to receive Wi-Fi signals from nearby access points. The Wi-Fimotion detector 212 may then detect a presence of user movement from thepreviously computed user location. More specifically, the Wi-Fi motiondetector 212 is configured to detect the subsequent user motion based onperiodic repeating of the steps of performing the primary wireless scanand performing the secondary wireless scans by the Wi-Fi scan module210. For example, the Wi-Fi scan module 210 is configured to perform theprimary wireless scan and the secondary wireless scans, repeatedly, toidentify respective set of access points and provision the result to theWi-Fi motion detector 212 for comparison of a shared number of accesspoints therebetween with a pre-defined threshold value to detect thesubsequent user motion as explained with reference to FIG. 3. An exampleswitching between the Wi-Fi motion detector 212 and the geolocationmotion detector 214 for detecting subsequent user motion is furtherexplained with reference to an illustrative example in FIG. 4.

FIG. 4 depicts a plurality of charts 400 associated with example motiondetection in accordance with embodiment. More specifically, theplurality of charts 400 includes a first plot 402 depicting timeintervals at which satellite scans are performed by the geolocationmotion detector 214, a second plot 404 depicting the time intervals atwhich wireless scans are performed by the Wi-Fi scan module 210 and athird plot 406 depicting user displacement (in meters) during the timeintervals corresponding to the first plot 402 and the second plot 404.The plurality of charts 400 is explained in further detail below:

The first plot 402 depicts a time line 408 on which time instants of thesatellite scans are plotted. For example, a satellite scan 410 isdepicted to be plotted on the time line 408 at the 0^(th) second timeinstant. It is understood that a time instant at which this initialsatellite scan is performed may be considered to be the 0^(th) secondtime instant for this illustrative example. The geolocation motiondetector 214 of the system 200 depicted in FIG. 2 may perform thesatellite scan 410 at the 0^(th) second time instant for receivinggeolocation signals corresponding to a current user location. A userlocation estimate may be computed based on the received geolocationsignals by the geolocation determination module 216 of the system 200.The geolocation motion detector 214 may perform another satellite scan412 at the 60^(th) second time instant (i.e. with a one minuteperiodicity). A corresponding displacement of a user associated with thesystem 200 is depicted to be 60 meters on the displacement axis 414 (asdepicted by displacement 416) corresponding to the third plot 406implying an average velocity estimate associated with the user movementsbetween the 0^(th) second time instant and the 60^(th) second timeinstant to be 1 meter/second. A user location estimate is computed basedon the received geolocation signals corresponding to the satellite scan412 and a difference between the new location estimate and the userlocation estimate corresponding to the satellite scan 410 is comparedwith a pre-defined distance threshold. In this illustrative example, thepre-defined distance threshold is chosen (for example, by the controllermodule 206 of the system 200) to be 100 meters. Since the difference of60 meters between the new user location estimate and the user locationestimate corresponding to the satellite scan 410 is less than thepre-defined distance threshold of 100 meters, it is determined by thecontroller module 206 that the user is relatively stationery or in a lowmobility condition. Accordingly, the controller module 206 is configuredto switch the detection of subsequent user motion to the Wi-Fi motiondetector 212. It is noted that if it was determined that the differencebetween the new location estimate and user location estimatecorresponding to the satellite scan 410 is greater than the pre-defineddistance threshold, then the controller module 206 would retain the useof geolocation motion detector 214 for detection of subsequent motion bycontinuing the satellite scanning at periodic one minute intervals.

Upon switching of the subsequent user motion detection to the Wi-Fimotion detector 212 by the controller module 206, the Wi-Fi scan module210 of the system 200 is configured to perform wireless scans for accesspoint identification at periodic intervals of 15 seconds as depicted bythe wireless scans 418, 420, 422, 424 and 426 corresponding to the75^(th), 90^(th), 105^(th), 120^(th) and 135^(th) second time instantson the time line 428 of the second plot 404. The wireless scan at the75^(th) second time instant may be considered to be primary wirelessscan and accordingly the new user location estimate computed at thesatellite scan 412 may be considered as the first user location estimatefor the current user location and access points identified in thevicinity of the current user location to be the first set of accesspoints. The subsequent wireless scans at the 90^(th), 105^(th) and120^(th) and 135^(th) second time instants correspond to the secondarywireless scans and accordingly access points identified at each of thesetime instants are compared with the access points identified during theprimary wireless scan and a number of shared access points at each timeinstant may be compared to a pre-defined threshold value. If the numberof shared access points is less than or equal to the pre-definedthreshold value for a pre-defined number of consecutive secondarywireless scans, then the Wi-Fi motion detector 212 detects the presenceof user motion. The detection of the absence of user motion or thepresence of user motion may be performed as explained with reference toFIG. 3 and is not explained herein again. At the 135^(th) second timeinstant, the Wi-Fi motion detector 212 is depicted to have detectedpresence of user motion. The corresponding user displacement from the75^(th) second time instant to the 135^(th) second time instant isdepicted by displacement 430 on the displacement axis 414. Upondetection of the user motion, the controller module 206 is configured toswitch to the geolocation motion detector 214, which performs thesatellite scan 432 at the 150^(th) second time instant to receive thegeolocation signals and the geolocation determination module 216determines a current user location estimate. The controller module 206is configured to compare the distance between this current user locationestimate with the previous user location estimate (i.e. new userlocation estimate) and based on the comparison, select one of Wi-Fimotion detector 212 and the geolocation motion detector 214 forsubsequent user motion detection as explained above.

Referring now to FIG. 2, in an embodiment, the geolocation motiondetector 214 is further configured to determine an average velocityestimate associated with the subsequent user motion. For example, in theillustrative example explained with reference to FIG. 4, the geolocationmotion detector 214 may detect the average velocity estimate associatedwith the user motion to be 1 meter/second. In an embodiment, aperiodicity of one of the Wi-Fi motion detector 212 and the geolocationmotion detector 214 is chosen based on the average velocity estimate.More specifically, the controller module 206 is configured to select thegeolocation motion detector 214 at high average velocities associatedwith user motion (implying that the user is traveling in a vehicle or isin general high mobility condition), with a periodicity chosen to beproportional to the average velocity estimate. For example, if the useris in a vehicle and accordingly an average velocity estimate associatedwith the user motion is high, then a periodicity of the geolocationmotion detector 214 may be chosen to be a higher value (for example,less than a minute periodicity for scanning of satellite signals).However, if the user is running or riding a bicycle, then a periodicityof the geolocation motion detector 214 may be chosen to be a lower value(for example, one minute periodicity for scanning of satellite signals).Similarly, a periodicity of the Wi-Fi motion detector 212 may be chosento be a high value (for example, 15 seconds) or a lower value (forexample, 5 to ten seconds) depending upon the average velocity estimatein the low mobility condition.

In an embodiment, the sensor module 208 of the system 200 is configuredto provision sensor indications of user movement at the user locationfor triggering the performing of the primary wireless scan at the userlocation. An example sensor module 208 may include an accelerometer todetect user movement. The sensor module 208 is configured to provisionan indication of user movement if the acceleration is greater than apreset threshold value. If the user motion is determined to be absent bythe geolocation motion detector 214 or the Wi-Fi motion detector 212 andthe user is deemed to be stationary, then the sensor indications of usermovement may trigger the Wi-Fi scan module 210 of the system 200 toinitiate the primary wireless scanning to identify the first set ofaccess points. In an embodiment, upon the selection of the Wi-Fi motiondetector 212 by the controller module 206 for user motion detection, theWi-Fi scan module 210 may perform wireless scans at periodic intervals.However, in between these wireless scans, if indication of user movementis received from the sensor module 208, then the Wi-Fi scan module 210may initiate the scanning process as explained with reference to FIG. 3for detection of user motion. The sensor assisted wireless scanning foruser motion detection enables the wireless scans to be performed with ahigher periodicity thereby further improving a power consumption of theelectronic device associated with the system 200. An example improvementin the power consumption on account of user motion detection based onWi-Fi scanning as well as sensor assistance in triggering Wi-Fi scanningis depicted in Table 1 below:

TABLE 1 Power Consumption in milliamperes (mA) Satellite Wi-Fi andSensor assisted based periodic Satellite Wi-Fi and Satellite locationbased location based location User Scenario estimation estimationestimation Stationery 20 1 0.1 Outdoor fast walk 20 16.5 16.6 (Averagevelocity = 1 meter/second) Outdoor typical 20 13.0 13.1 walk (Averagevelocity = 0.5 meter/second) Indoor Pedestrian 20 1 1.1 (WithinOffice/home) Vehicular 20 20 20.1

As depicted in table 1, the conventional satellite (GNSS) based periodiclocation estimation using one-minute periodicity scanning for satellitesignals consumes 20 mA irrespective of user's location context. However,using Wi-Fi and satellite based location estimation (i.e. using Wi-Fiscans to determine if the user has moved or not and then modulating thecall to geolocation module 204 based on user motion detection) assuggested in various embodiments herein provide significant powersavings in both stationary and indoor scenarios as depicted in Table 1above. The stationary and indoor scenario is historically the mostdominant use case applicable to typical users for more than 60% of thetime. Moreover, the sensor assisted Wi-Fi and satellite based locationestimation provides a further improvement in power saving as depicted bythe Table 1 above.

As explained, the system 200 may be included within a electronic device,such as a handheld device like a mobile phone, a Smartphone, a laptopand a tablet computer and/or wearable or an accessory like a watch, apair of glasses and the like. The electronic device and/or the system200 may include components for performing various functions, which arenot depicted herein. For example, the electronic device and/or thesystem 200 may additionally include components, such as an input unit(e.g., a touch screen panel or a keyboard/keypad), a video display unit(e.g., liquid crystal display (LCD), a cathode ray tube (CRT), and thelike), a cursor control device (e.g., a mouse), a drive unit (e.g., adisk drive), a signal generation unit (e.g., a speaker) and/or a networkinterface unit. The drive unit includes a machine-readable medium uponwhich is stored one or more sets of instructions (e.g., software)embodying one or more of the methodologies and/or functions describedherein. In an embodiment, the software resides, either completely orpartially, within the controller module 206, and/or within the Wi-Fimodule 202 and the geolocation module 204 during the execution thereofby the system 200, such that the controller module 206, the Wi-Fi module202 and the geolocation module 204 also constitute a machine-readablemedia. The software may further be transmitted and/or received over anetwork via the network interface unit. A location estimation method isexplained with reference to FIG. 5.

FIG. 5 illustrates a flow diagram of a first example location estimationmethod 500 (hereinafter referred to as method 500) in accordance with anexample embodiment. The method 500 depicted in the flow diagram may beexecuted by, for example, by a location estimation device including alocation estimation system, such as the system 200 explained withreference to FIGS. 2 to 4. Operations of the flowchart, and combinationsof operation in the flowchart, may be implemented by, for example,hardware, firmware, a processor, circuitry and/or a different deviceassociated with the execution of software that includes one or morecomputer program instructions. The operations of the method 500 aredescribed herein with help of the location estimation device. However,the operations of the method 500 can be described and/or practiced byusing any device other than the location estimation device. The method500 starts at operation 502.

At operation 502, a primary wireless scan is performed (for example,with a location estimation device including a transceiver, such as theWi-Fi scan module 210 of the system 200) to identify a first set ofaccess points at a user location. The user location is associated with afirst user location estimate. In an example scenario, the first userlocation estimate, such as a three-dimensional location estimate of theuser may have been previously computed, for example by usingtriangulation of geolocation signals received from three or moresatellites (for example, signals received from GNSS satellites), and assuch, the first user location estimate of the user may already be knownprior to performing the primary wireless scan. In an embodiment, thefirst user location estimate may have been computed using Wi-Fi basedpositioning (for example, using RSSI or TOF measurements from nearbyaccess points), prior to performing the primary wireless scan.

At operation 504, a secondary wireless scan is performed at pre-definedtime intervals subsequent to the primary wireless scan (for example, bya location estimation device including a transceiver, such as the Wi-Fiscan module 210 of the system 200). A set of access points is identifiedcorresponding to each secondary wireless scan. In an illustrativeexample, a pre-defined time interval may be chosen to be ten seconds. Itis understood that the pre-defined time interval of ten seconds isincluded herein for illustration purposes and that the pre-defined timeinterval may be chosen to be any such time interval based on empiricaldata. Accordingly, a secondary wireless scans is performed at every tensecond interval (for example, at 10, 20, 30 seconds and so on and soforth) from the completion of the primary wireless scan.

In an embodiment, the method 500 further includes detecting a presenceof one or more mobile access points (for example, with a locationestimation device). As explained with reference to FIG. 2, the term‘mobile access point’ refers to a non-stationary access point identifiedto be present across one or more distant locations. For example, anaccess point deployed in a vehicle of the user or in one or more otherelectronic devices associated with the user and functioning as accesspoints and the like may be identified as mobile access points. In anembodiment, the method 500 further includes eliminating the one or moremobile access points from the first set of access points and the set ofaccess points corresponding to the each secondary wireless scan if theone or more mobile access points are detected to be present.

In an embodiment, the method 500 further includes identifying (forexample, with the location estimation device) a presence of one or moreduplicate entries in the first set of access points and the set ofaccess points corresponding to the each secondary wireless scan,respectively, by disregarding last nibble of media access control (MAC)identification (IDs) during access point identification. As explainedwith reference to FIG. 2, a same physical access point may advertisemultiple MAC IDs, which differ only in their last nibble (e.g. lastgroup of alphanumeric characters from among a plurality of alphanumericcharacters configuring MAC IDs). As a result, a same physical accesspoint may be wrongly interpreted as different access points and beincluded multiple times during wireless scanning. Accordingly, the lastnibble of the MAC IDs may be disregarded during wireless scanning, whichmay result in one or more duplicate entries in the first set of accesspoints as well as in each set of access points identified during one ormore secondary wireless scans. In an embodiment, the method 500 furtherincludes coalescing the one or more duplicate entries in the first setof access points and the set of access points corresponding to the eachsecondary wireless scan, respectively, if the one or more duplicateaccess points are identified to be present.

In an embodiment, the method 500 further includes identifying (forexample, with the location estimation device), for each secondarywireless scan, a number of shared access points between the first set ofaccess points and a set of access points corresponding to each secondarywireless scan. The method 500 further includes comparing the number ofshared access points with a pre-defined threshold value.

In an example scenario, the pre-defined threshold value may be chosenbased on empirical data associated with various types of environment(for example, indoor environment, outdoor environment, ruralenvironment, urban or semi-urban environment and the like). For example,in areas with high access point density, the pre-defined threshold valuemay be chosen to be a higher number (for example, two or greater thantwo), whereas an area with lower access point density, the pre-definedthreshold value may be chosen to be a smaller number (for example, zeroor one). In an embodiment, the pre-defined threshold value may bedetermined based on an expected number of mobile access points in thesurrounding area.

At operation 506, the method 500 includes detection (for example, withthe location estimation device) of: (1) a presence of user motion if thenumber of shared access points is less than or equal to the pre-definedthreshold value for a pre-defined number of consecutive secondarywireless scans, or (2) an absence of the user motion from the userlocation if the number of shared access points is greater than thepre-defined threshold value for the pre-defined number of consecutivesecondary wireless scans. The detection of user motion based on thecomparison of the shared number of access points and the pre-definedthreshold value may be performed as explained with reference to anillustrative example in FIG. 3 and is not explained herein.

In an embodiment, the method 500 further includes computing (forexample, by the location estimation device), for each secondary wirelessscan, a difference in received signal strength indication (RSSI)measurements between the first set of access points and a set of accesspoints corresponding to the each secondary wireless scan to assist indetection of the user motion with finer resolution. For example, inaddition to the number of shared access points, a difference in RSSI (ortime of flight or TOF) measurements may be computed to assist indetection of user motion. For example, if an RSSI measurement receivedfrom an access point is observed to be decreasing over consecutivesecondary wireless scans, then it may be deduced that the user is movingaway from the access point and accordingly, user motion may be detectedwith greater granularity based on difference in RSSI measurements.

At operation 508, a current user location is estimated (for example, bythe location estimation device) based on (1) the first user locationestimate if the user motion is detected to be absent, or (2) a seconduser location estimate computed based on geolocation signals (such asfor example, global navigation satellite system (GNSS) signals) if theuser motion is detected to be present. More specifically, the initiallycomputed first user location estimate is propagated if the presence ofuser motion is detected to be absent. Accordingly, a location of theuser may be estimated to be user location associated with the first userlocation estimate. The one or more applications in the electronic deviceand/or in the location estimation device may utilize the estimatedlocation of the user for triggering one or more specific actions at anapplication level upon a user's arrival at, or, departure from, areas ofinterest. However, if a presence of the user motion to a new userlocation is detected, then a second user location estimate may becomputed (for example, by the location estimation device) based ongeolocation signals received at the new user location. For example, ifit is determined that the user has moved from the floor 106 to thestreet 116 depicted in the environment 100 in FIG. 1, then the seconduser location estimate may be estimated based on the receivedgeolocation signals at the user location on the street 116.

In an embodiment, the method 500 further includes detecting if adifference between the second user location estimate and the first userlocation estimate (also referred to herein as the new user locationestimate and the old user location estimate, respectively) is greaterthan a pre-defined distance threshold. In an embodiment, the subsequentuser motion is detected based on the difference between the new userlocation estimate and the old user location estimate. In an embodiment,if the difference between the new user location estimate and the olduser location estimate is greater than the pre-defined distancethreshold, implying that the user is moving with a higher velocity, thenthe subsequent user motion detection is performed based on geolocationsignals with associated periodicity to detect subsequent user motion. Inan example embodiment, the periodicity may be one-minute interval,implying a satellite scan every minute to receive geolocation signalsfrom the satellites. The user locations may be computed at every minuteto check for presence of user movement from the previously computed userlocation to detect subsequent user motion.

In an embodiment, if the difference between the new user locationestimate and the old user location estimate is less than or equal to thepre-defined distance threshold, implying, that the user is eitherstationary or moving with a relatively lower velocity, then thesubsequent user motion is detected based on Wi-Fi signals withassociated periodicity. In an example embodiment, the periodicityassociated with the Wi-Fi signals may be 15 seconds interval, implying awireless scan every 15 seconds to receive Wi-Fi signals from nearbyaccess points. The detection of the subsequent user motion may beperformed based on periodic repeating of the steps of performing theprimary wireless scan, performing the secondary wireless scans anddetecting one of the presence and the absence of the subsequent usermotion. The detection of subsequent user motion may be performed asexplained with reference to an illustrative example in FIG. 4 and is notexplained herein for sake of brevity.

In an embodiment, the method 500 further includes determining an averagevelocity estimate associated with the subsequent user motion. In anembodiment, a periodicity of one of the Wi-Fi signals based user motiondetection and the geolocation signals based user motion detection ischosen based on the average velocity estimate. In an embodiment, themethod 500 includes receiving sensor indications of user movement at theuser location and triggering the performing of the primary wireless scanat the user location. For example, an indication of user movement may bereceived from an accelerometer if the acceleration is greater than apreset threshold value. The indication of user movement may trigger theprimary wireless scanning to identify the first set of access points.The sensor assisted wireless scanning for user motion detection enablesthe wireless scans to be performed with a higher periodicity therebyfurther improving a power consumption of the location estimation device.Another example method of location estimation is explained withreference to FIGS. 6A and 6B.

FIGS. 6A and 6B illustrate a flow diagram of a second example locationestimation method 600 (hereinafter referred to as method 600) inaccordance with an example embodiment. The method 600 depicted in theflow diagram may be executed by, for example, with a location estimationdevice including a location estimation system, such as the system 200explained with reference to FIGS. 2 to 4. Operations of the flowchart,and combinations of operation in the flowchart, may be implemented by,for example, hardware, firmware, a processor, circuitry and/or adifferent device associated with the execution of software that includesone or more computer program instructions. The operations of the method600 are described herein with help of the location estimation device.However, the operations of the method 600 can be described and/orpracticed by using any device other than the location estimation device.The method 600 starts at operation 602.

At operation 602, a first user location estimate is determinedcorresponding to a user location using GNSS signals (for example, withthe location estimation device using a location determination module,such as the geolocation determination module 216 of the system 200). Itis understood that the first user location estimate may be computedusing standard techniques such as, for example, using triangulation ofGNSS signals received from three or more GNSS satellites. At operation604, a GNSS scan after a pre-defined time interval is performed (forexample, with the location estimation device using a geolocation motiondetector, such as the geolocation motion detector 214 of the system 200)and a second user location estimate is computed based on received GNSSsignals. At operation 606, a difference between the first user locationestimate and the second user location estimate is compared with apre-defined distance threshold. The pre-defined distance threshold maybe chosen to be any number based on empirical data. For example, thepre-defined threshold value may be chosen to be 100 meters as explainedwith reference to an illustrative example in FIG. 4.

If it is determined that the difference between the first user locationestimate and the second user location estimate is greater than thepre-defined distance threshold, then operation 608 is performed. Atoperation 608, the user is determined to be in motion if the differencebetween the first user location estimate and the second user locationestimate is greater than the pre-defined distance threshold. Further atoperation 608, periodic GNSS scans are performed to determinecorresponding user location estimates till the difference between acurrent user location estimate (corresponding to a current userlocation) and immediately previous user location estimate is less thanor equal to the pre-defined distance threshold. Upon determining that adifference between the current user location estimate and theimmediately previous user location estimate is less than or equal to thepre-defined distance threshold, it is determined that the user isstationary and operation 612 is performed thereafter.

If it is determined that the difference between the first user locationestimate and the second user location estimate is less than or equal tothe pre-defined distance threshold, then operation 610 is performed. Atoperation 610, the user is determined to be stationary at a current userlocation if the difference between the first user location estimate andthe second user location estimate is lesser than the pre-defineddistance threshold. Further, at operation 610, user's location isestimated based on the second user location estimate and the second userlocation estimate is hereinafter propagated as a current user locationestimate. Subsequently, operation 612 is performed.

At operation 612, sensor measurements are performed (for example, withthe location estimation device using a sensor device such as the sensormodule 208 of the system 200) to detect indications of user movementsfrom the current user location estimate. At operation 614, indicationsof user movements based on sensor measurements are determined. If noindications of user movements are determined from the sensormeasurements, then the operation 616 is performed. At operation 616, theuser is determined to be stationary and the user's location is estimatedbased on the current location estimate. Thereafter, operations 612 and614 are repeated till the indications of user movements are determinedat operation 614. If indications of user movements are determined fromthe sensor measurements, then operation 618 is performed. At operation618, a primary wireless scan is performed (for example, with thelocation estimation device, using a transceiver, such as the Wi-Fi scanmodule 210) to identify a first set of access points associated with thecurrent user location estimate. At operation 620, secondary wirelessscans are performed at pre-defined time intervals subsequent to theprimary wireless scan (for example, by the location estimation device,using a transceiver, such as the Wi-Fi scan module 210) to identifyrespective set of access points. For each secondary wireless scan, anumber of shared access points between the first set of access pointsand a set of access points corresponding to the each secondary wirelessscan is identified and compared with a pre-defined threshold value (forexample, with the location estimation device).

At operation 622, it is determined whether the number of shared accesspoints is greater than the pre-defined threshold value for a pre-definednumber of consecutive secondary wireless scans. If is determined thatthe number of shared access points is not greater than the pre-definedthreshold value for a pre-defined number of consecutive secondarywireless scans, then operation 624 is performed. At operation 624, anabsence of user motion from the current user location is determined.Thereafter, at operation 626, the user's location is estimated based onthe current user location estimate. If is determined that the number ofshared access points is greater than the pre-defined threshold value fora pre-defined number of consecutive secondary wireless scans, thenoperation 628 is performed. At operation 628, a presence of user motionfrom the current user location to a new user location is determined. Atoperation 630, the user's location is estimated based on a new userlocation estimate computed based on GNSS signals received at the newuser location.

As explained with reference to FIG. 2, techniques of user motiondetection based on access point visibility during successive wirelessscans may be extended to other applications such as tracking of assetslike objects stored in a warehouse and the like. A method for estimatinga location of an object based on object motion detection is explainedwith reference to FIG. 7.

FIG. 7 illustrates a flow diagram of a method 700 for estimating alocation of an object based on object motion detection in accordancewith an example embodiment. The method 700 depicted in the flow diagrammay be executed by, for example, by an electronic device including alocation estimation device, such as the system 200 explained withreference to FIGS. 2 to 4. In such a case, the electronic device may beembodied as a physical device including components of the system 200explained with reference to FIG. 2 and such a device may be tagged withobjects, whose motion is to be tracked for location estimation purposes.Operations of the flowchart, and combinations of operation in theflowchart, may be implemented by, for example, hardware, firmware, aprocessor, circuitry and/or a different device associated with theexecution of software that includes one or more computer programinstructions. The operations of the method 700 are described herein withhelp of the electronic device. However, the operations of the method 700can be described and/or practiced by using any device other than theelectronic device. For example, tags including components such as thoseincluded in the system 200 may be affixed with objects to be tracked forlocation estimation purposes. Further, the term ‘object’ as used hereinmay refer to any physical good, whose location is to be tracked. Forexample, a location of physical good or object stored in a warehouse mayneed to be continuously ascertained for theft or pilferage reasons.Accordingly, a presence of motion (or lack of motion therefrom) ischecked for objects for corresponding location estimation purposes. Themethod 700 starts at operation 702.

At operation 702, a primary wireless scan is performed (for example,with an electronic device including a transceiver, such as the Wi-Fiscan module 210 of the system 200) to identify a first set of accesspoints at an object location. The object location is associated with afirst object location estimate (for example, a location of a warehousestoring the object). In an example scenario, the first object locationestimate, such as a three-dimensional location estimate of the warehousemay have been previously computed, for example by using triangulation ofgeolocation signals received from three or more satellites (for example,signals received from GNSS satellites), and as such, the first objectlocation estimate of the object (i.e. the warehouse) may already beknown prior to performing the primary wireless scan. In an embodiment,the first object location estimate may have been computed using Wi-Fibased positioning (for example, using RSSI or TOF measurements fromnearby access points), prior to performing the primary wireless scan. Inan embodiment, the first object location estimate may just be areference location (for example, can be taken as the origin), as changesfrom the reference location may be of interest than the absolutelocation itself.

At operation 704, a secondary wireless scan is performed at pre-definedtime intervals subsequent to the primary wireless scan (for example, bythe electronic device including a transceiver, such as the Wi-Fi scanmodule 210 of the system 200). A set of access points is identifiedcorresponding to each secondary wireless scan. In an illustrativeexample, a pre-defined time interval may be chosen to be ten seconds. Itis understood that the pre-defined time interval of ten seconds isincluded herein for illustration purposes and that the pre-defined timeinterval may be chosen to be any such time interval based on empiricaldata. Accordingly, a wireless scan is performed at every ten secondinterval (for example, at 10, 20, 30 seconds and so on and so forth)from the completion of the primary wireless scan.

In an embodiment, the method 700 further includes detecting a presenceof one or more mobile access points and eliminating the one or moremobile access points from the first set of access points and the set ofaccess points corresponding to the each secondary wireless scan if theone or more mobile access points are detected to be present. In anembodiment, the method 700 further includes identifying a presence ofone or more duplicate entries in the first set of access points and theset of access points corresponding to the each secondary wireless scan,respectively, by disregarding last nibble of media access control (MAC)identification (IDs) during access point identification. Further, themethod 700 further includes coalescing the one or more duplicate entriesin the first set of access points and the set of access pointscorresponding to the each secondary wireless scan, respectively, if theone or more duplicate access points are identified to be present.

In an embodiment, the method 700 further includes identifying (forexample, with the location estimation device), for each secondarywireless scan, a number of shared access points between the first set ofaccess points and a set of access points corresponding to each secondarywireless scan. The method 700 further includes comparing the number ofshared access points with a pre-defined threshold value. In an examplescenario, the pre-defined threshold value may be chosen based onempirical data associated with various types of environment as explainedwith reference to FIG. 5.

At operation 706, the method 700 includes detection (for example, withthe electronic device) of: (1) a presence of object motion if the numberof shared access points is less than or equal to the pre-definedthreshold value for a pre-defined number of consecutive secondarywireless scans, or (2) an absence of the object motion from the objectlocation if the number of shared access points is greater than thepre-defined threshold value for the pre-defined number of consecutivesecondary wireless scans. The detection of object motion based on thecomparison of the shared number of access points and the pre-definedthreshold value may be performed as explained with reference to anillustrative example in FIG. 3 and is not explained herein. Detectingthe absence or presence of motion of the object may enable ascertainingthe location of the object and as such may help in tracking of assets.

Without in any way limiting the scope, interpretation, or application ofthe claims appearing below, advantages of one or more of the exampleembodiments disclosed herein include low-power estimation of location ofusers/objects. Accordingly, Wi-Fi signals and geolocation signals basedpositioning are collectively utilized in location estimation. Morespecifically, Wi-Fi scans are used to determine if the user has moved ornot. This is then used to modulate the call to geolocation determinationmodule for location estimation. This decreases power consumptionsignificantly in indoor pedestrian and stationary conditions. This isespecially useful for handheld device applications like location basedadvertising, social networking, reminder services and the like, whichare configured to be executed continuously at the application layerbackend for monitoring a user's locations and trigger specific actionsat an application level upon a user's arrival at, or, departure from,areas of interest. Further techniques disclosed herein facilitate sensorassisted wireless scanning for user motion detection, which in turnenables the wireless scans to be performed with a lower periodicitythereby further improving a power consumption of the electronic devices.Furthermore, the methods and systems disclosed herein do not necessitatea provision of an access point database for location estimation, therebyprecluding additional deployment cost. Further, the methods and systemsmay be implemented without requiring host intervention. Also, themethods and systems disclosed herein are configured to discriminate usermotion at granularity of static/low motion versus high rate motion andprovide power conservation (for example, better power conservation thansensor based motion detectors). In some example scenarios, the powerconsumption is less than 1 mA compared to nearly 20 mA when GNSS basedlocation estimation is utilized alone for estimating a user's location.Moreover, the location estimation techniques as disclosed herein may beused in a variety of applications, such as geofencing applications(e.g., tracking of goods/products in transit etc.). In some embodiments,the geolocation signals based location estimation may be precluded andWi-Fi based motion detection as disclosed herein may be utilized tocheck on illegal movement of goods in storage, such as a warehouse andto implement corrective actions as explained with reference to FIG. 7.

Although the present technology has been described with reference tospecific example embodiments, it is noted that various modifications andchanges may be made to these embodiments without departing from thebroad spirit and scope of the present technology. For example, thevarious devices, modules etc., described herein may be enabled andoperated using hardware circuitry (for example, complementary metaloxide semiconductor (CMOS) based logic circuitry), firmware, softwareand/or any combination of hardware, firmware, and/or software (forexample, embodied in a machine-readable medium). For example, thevarious electrical structures and methods may be embodied usingtransistors, logic gates, and electrical circuits (for example,application specific integrated circuit (ASIC) circuitry and/or inDigital Signal Processor (DSP) circuitry). Particularly, the system 200,the Wi-Fi module 202, the geolocation module 204, the controller module206 and the sensor module 208 may be enabled using software and/or usingtransistors, logic gates, and electrical circuits (for example,integrated circuit circuitry such as ASIC circuitry).

Also, techniques, devices, subsystems and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present technology.Other items shown or discussed as directly coupled or communicating witheach other may be coupled through some interface or device, such thatthe items may no longer be considered directly coupled with each otherbut may still be indirectly coupled and in communication, whetherelectrically, mechanically, or otherwise, with one another. Otherexamples of changes, substitutions, and alterations ascertainable by oneskilled in the art, upon or subsequent to studying the exampleembodiments disclosed herein, may be made without departing from thespirit and scope of the present technology.

It should be noted that reference throughout this specification tofeatures, advantages, or similar language does not imply that all of thefeatures and advantages should be or are in any single embodiment.Rather, language referring to the features and advantages may beunderstood to mean that a specific feature, advantage, or characteristicdescribed in connection with an embodiment may be included in at leastone embodiment of the present technology. Thus, discussions of thefeatures and advantages, and similar language, throughout thisspecification may, but do not necessarily, refer to the same embodiment.

Various embodiments of the present disclosure, as discussed above, maybe practiced with steps and/or operations in a different order, and/orwith hardware elements in configurations which are different than thosewhich are disclosed. Therefore, although the technology has beendescribed based upon these example embodiments, it is noted that certainmodifications, variations, and alternative constructions may be apparentand well within the spirit and scope of the technology. Although variousexample embodiments of the present technology are described herein in alanguage specific to structural features and/or methodological acts, thesubject matter defined in the appended claims is not necessarily limitedto the specific features or acts described above. Rather, the specificfeatures and acts described above are disclosed as example forms ofimplementing the claims.

What is claimed is:
 1. A location estimation method comprising:performing a primary wireless scan to identify a first set of accesspoints at a user location, the user location associated with a firstuser location estimate; performing a secondary wireless scan atpre-defined time intervals subsequent to the primary wireless scan,wherein a set of access points is identified corresponding to eachsecondary wireless scan, and wherein for each secondary wireless scan, anumber of shared access points is identified and compared with apre-defined threshold value, a shared access point being an access pointidentified to be present in the first set of access points and the setof access points corresponding to the secondary wireless scan; detectingwith a location estimation device: a presence of user motion if thenumber of shared access points is less than or equal to the pre-definedthreshold value for a pre-defined number of consecutive secondarywireless scans, or an absence of the user motion from the user locationif the number of shared access points is greater than the pre-definedthreshold value for the pre-defined number of consecutive secondarywireless scans; and estimating a current user location with the locationestimation device, based on: the first user location estimate if theabsence of the user motion is detected, or a second user locationestimate computed based on geolocation signals if the presence of theuser motion is detected.
 2. The method of claim 1, further comprising:detecting a presence of one or more mobile access points, wherein amobile access point corresponds to a non-stationary access pointidentified to be present across one or more distant locations; andeliminating the one or more mobile access points from the first set ofaccess points and the set of access points corresponding to thesecondary wireless scan if the one or more mobile access points aredetected to be present.
 3. The method of claim 1, further comprising:identifying a presence of one or more duplicate entries in the first setof access points and the set of access points corresponding to thesecondary wireless scan, respectively, by disregarding last nibble ofmedia access control (MAC) identification (ID) during access pointidentification; and coalescing the one or more duplicate entries in thefirst set of access points and the set of access points corresponding tothe secondary wireless scan, respectively, if the one or more duplicateaccess points are identified to be present.
 4. The method of claim 1,further comprising: detecting, with the location estimation device, if adifference between the second user location estimate and the first userlocation estimate is greater than a pre-defined distance threshold; anddetecting subsequent user motion, with the location estimation device,based on: Wi-Fi signals if the difference between the second userlocation estimate and the first user location estimate is less than orequal to the pre-defined distance threshold, or geolocation signals ifthe difference between the second user location estimate and the firstuser location estimate is greater than the pre-defined distancethreshold.
 5. The method of claim 4, further comprising determining anaverage velocity estimate associated with the subsequent user motion bythe location estimation device, wherein a periodicity of one of theWi-Fi signals based subsequent user motion detection and the geolocationsignals based subsequent user motion detection is chosen based on theaverage velocity estimate.
 6. The method of claim 1, wherein for eachsecondary wireless scan, a difference in received signal strengthindication (RSSI) measurements between the first set of access pointsand the set of access points corresponding to the secondary wirelessscan is computed to assist in detection of the user motion with finerresolution.
 7. The method of claim 1, further comprising: receivingsensor indications of user movement at the user location; and triggeringthe performing of the primary wireless scan upon receiving the sensorindications of the user movement.
 8. The method of claim 1, wherein thefirst user location estimate corresponding to the user location iscomputed with the location estimation device based on geolocationsignals received at the user location.
 9. A location estimation systemcomprising: a Wi-Fi module comprising: a Wi-Fi scan module configured toperform: a primary wireless scan to identify a first set of accesspoints at a user location, the user location associated with a firstuser location estimate, and a secondary wireless scan at pre-definedtime intervals subsequent to the primary wireless scan, wherein a set ofaccess points is identified corresponding to each secondary wirelessscan, and a Wi-Fi motion detector communicatively associated with theWi-Fi scan module and configured to identify a number of shared accesspoints for each secondary wireless scan, a shared access point being anaccess point identified to be present in the first set of access pointsand the set of access points corresponding to the secondary wirelessscan, the Wi-Fi motion detector further configured to compare the numberof shared access points with a pre-defined threshold value to therebyidentify: a presence of user motion if the number of shared accesspoints is less than or equal to the pre-defined threshold value for apre-defined number of consecutive secondary wireless scans, or anabsence of the user motion from the user location if the number ofshared access points is greater than the pre-defined threshold value forthe pre-defined number of consecutive secondary wireless scans; ageolocation module communicatively associated with the Wi-Fi module andcomprising a geolocation determination module, the geolocationdetermination module configured to estimate a current user locationbased on: the first user location estimate if the absence of the usermotion is detected, or a second user location estimate computed based ongeolocation signals if the presence of the user motion is detected. 10.The system of claim 9, wherein the Wi-Fi motion detector is furtherconfigured to: detect a presence of one or more mobile access points,wherein a mobile access point corresponds to a non-stationary accesspoint identified to be present across one or more distant locations; andeliminate the one or more mobile access points from the first set ofaccess points and the set of access points corresponding to thesecondary wireless scan if the one or more mobile access points aredetected to be present.
 11. The system of claim 9, wherein the Wi-Fimotion detector is further configured to: identify a presence of one ormore duplicate entries in the first set of access points and the set ofaccess points corresponding to the secondary wireless scan,respectively, by disregarding last nibble of media access control (MAC)identification (ID) during access point identification; and coalesce theone or more duplicate entries in the first set of access points and theset of access points corresponding to the secondary wireless scan,respectively, if the one or more duplicate access points are identifiedto be present.
 12. The system of claim 9, further comprising acontroller module communicatively associated with the Wi-Fi module andthe geolocation module, the controller module configured to: detect if adifference between the first user location estimate and the second userlocation estimate is greater than a pre-defined distance threshold; andfacilitate detection of subsequent user motion by selecting: the Wi-Fimotion detector if the difference between the second user locationestimate and the first user location estimate is less than or equal tothe pre-defined distance threshold, or a geolocation motion detectorassociated with the geolocation module if the difference between thesecond user location estimate and the first user location estimate isgreater than the pre-defined distance threshold.
 13. The system of claim12, wherein the geolocation motion detector is further configured todetermine an average velocity estimate associated with the subsequentuser motion, wherein a periodicity of one of the Wi-Fi motion detectorand the geolocation motion detector is chosen based on the averagevelocity estimate.
 14. The system of claim 9, wherein Wi-Fi motiondetector is further configured to compute, for each secondary wirelessscan, a difference in received signal strength indication (RSSI)measurements between the first set of access points and the set ofaccess points corresponding to the secondary wireless scan to assist indetection of the user motion with finer resolution.
 15. The system ofclaim 9, further comprising a sensor module configured to provisionsensor indications of user movement at the user location for triggeringthe performing of the primary wireless scan at the user location. 16.The system of claim 9, wherein the first user location estimatecorresponding to the user location is computed by the geolocationdetermination module based on geolocation signals received at the userlocation.
 17. The system of claim 9, wherein the system is at leastpartially embodied as an integrated circuit.
 18. A method comprising:performing a primary wireless scan to identify a first set of accesspoints at an object location, the object location associated with afirst object location estimate; performing a secondary wireless scan atpre-defined time intervals subsequent to the primary wireless scan,wherein a set of access points is identified corresponding to eachsecondary wireless scan, and wherein for each secondary wireless scan, anumber of shared access points is identified and compared with apre-defined threshold value, a shared access point being an access pointidentified to be present in the first set of access points and the setof access points corresponding to the secondary wireless scan; anddetecting with an electronic device: a presence of object motion if thenumber of shared access points is less than or equal to the pre-definedthreshold value for a pre-defined number of consecutive secondarywireless scans, or an absence of the object motion from the objectlocation if the number of shared access points is greater than thepre-defined threshold value for the pre-defined number of consecutivesecondary wireless scans.
 19. The method of claim 18, furthercomprising: detecting a presence of one or more mobile access points,wherein a mobile access point corresponds to a non-stationary accesspoint identified to be present across one or more distant locations; andeliminating the one or more mobile access points from the first set ofaccess points and the set of access points corresponding to thesecondary wireless scan if the one or more mobile access points aredetected to be present.
 20. The method of claim 18, further comprising:identifying a presence of one or more duplicate entries in the first setof access points and the set of access points corresponding to thesecondary wireless scan, respectively, by disregarding last nibble ofmedia access control (MAC) identification (ID) during access pointidentification; and coalescing the one or more duplicate entries in thefirst set of access points and the set of access points corresponding tothe secondary wireless scan, respectively, if the one or more duplicateaccess points are identified to be present.